非数据辅助的 QAM 信号载波频偏估计算法

摘要

A non-data-aided frequency offset estimation algorithm of Quadrature Amplitude Modulated (QAM)signal is inves-tigated.Considering the applicable constraint with the low-order QAMsignals and high calculation complexity of most frequency offset estimation algorithms,a frequency offset estimation algorithm with the weighted phase histogram is proposed.According to the relation between the phase probability density function of zero frequency offset and the weighted phase histogram,and intro-ducing the multistage estimation algorithm,the peak of second-order moment of the histogram is measured,the frequency offset estimation value can be obtained.Further,the algorithm realizes the process of multistage estimation introducing with the Fast Fourier Transform algorithm.As a result,the calculation processing is simplified and the calculation complexity is reduced.Some simulation results show that the proposed algorithm has perfect estimation performance without the additional information including with the signal-to-noise ratio and constellation and pilots while the signal-to-noise ratio is high.%研究了正交幅度调制（Quadrature Amplitude Modulated，QAM）信号的非数据辅助载波频率偏移估计算法。针对一些算法主要适用于低阶 QAM信号以及计算复杂度较高等问题，提出一种基于加权相位直方图的载波频偏估计算法。该算法通过分析零频偏下的相位概率密度函数与加权相位直方图的关系，采用多级估计方法，对该相位直方图二阶矩的峰值进行测量，从而得到频偏估计值。进一步地，本算法通过联合快速傅里叶变换（Fast Fourier Transform，FFT）算法实现多级估计过程，从而简化计算过程降低计算复杂度。仿真结果表明，信噪比较高时，该算法在无信噪比、星座图以及前导信息等辅助信息条件下同样具有较好的估计性能。